kbhit() function for bare metal

Hi chipslinger,

For the LX9 MicroBoard, which used MicroBlaze, we wrote our own line handler function.  Keep in mind, that hardware design used a UARTLite device instead of the PS UART so there is a call to XUartLite_Recv() to get the contents of the UART receive buffer which was non-blocking.  In looking through the Zynq Standalone BSP, it looks like there is a similar function for the PS UART code file xuartps.c named XUartPs_Recv() which is also non-blocking.

// ---------------------------------------------------------------------------
int my_get_line_poll(char * line, int maxlen)
{
    int buffer_index;
    char character_copy = 0;
    u8 DataBuffer[MAX_LINE_LENGTH];
    unsigned int received_char_count = 0;
    static unsigned int total_received_char_count = 0;
   
    // Make a call to UartLite instance to check for new characters
    // coming in.
    received_char_count = XUartLite_Recv(&UartLite, DataBuffer, (MAX_LINE_LENGTH - received_char_count));
   
    // Check to see if there were any characters received, otherwise return.
    if (received_char_count > 0)
    {
        for (buffer_index = 0; buffer_index < received_char_count; buffer_index++)
        {
            // Make sure that the line length has not been reached.
            if (total_received_char_count == MAX_LINE_LENGTH)
            {
                // Force a line feed character, this is the end of the
                // line that is being polled for.
                outbyte('r');
                outbyte('
');
                // Null terminate the string so that it is still a
                // valid string.
                line[total_received_char_count] = 0;
                // Reset the total character count in preparation for the
                // next line yet to be received.
                total_received_char_count = 0;
                // Return the total count of characters in the current line.
                return MAX_LINE_LENGTH;
            }
            // Get the next character that was received from the Uart Lite
            // device.
            character_copy = (char) DataBuffer[buffer_index];
           
            // Determine what action to take with the next received
            // character.
            if (character_copy == '
')
            {
                // Ignore it.
                ;
            }
            else if (character_copy == 'r')
            {
                // A line feed character has been encountered, this is the
                // end of the line that is being polled for.
                outbyte('r');
                outbyte('
');
                // Null terminate the string so that it is still a
                // valid string.
                line[total_received_char_count] = 0;
                // Determine the number of characters that are in the line.
                received_char_count = total_received_char_count;
                // Reset the total character count in preparation for the
                // next line yet to be received.
                total_received_char_count = 0;
                // Return the total count of characters in the current line.
                return received_char_count;
            }
            // Check for backspace or delete key.
            else if ((character_copy == 'b') || (character_copy == 0x7F))
            {
                if (total_received_char_count > 0)
                {
                    outbyte('b'); // Write backspace
                    outbyte(' ');  // Write space
                    outbyte('b'); // Write backspace
                    total_received_char_count--;
                    line[total_received_char_count] = 0;
                }
            }
            // Check for escape key or control-U.
            else if ((character_copy == 0x1b) || (character_copy == 0x15))
            {
                while (total_received_char_count > 0)
                {
                    outbyte('b'); // Write backspace
                    outbyte(' ');  // Write space
                    outbyte('b'); // Write backspace
                    total_received_char_count--;
                    line[total_received_char_count] = 0;
                }
            }
            else
            {
                // Echo character back to the user.
                outbyte(character_copy);
                line[total_received_char_count] = character_copy;
                total_received_char_count++;
            }
        }
    }
   
    return -1;
}

YIKES! Sorry about the way this forum mangles this C code, hopefully it is still somewhat readable on the other end.

The intent of this function was to poll until a complete line with carriage return character was entered.  However, maybe doing something similar but limited to a single character would help you with what you need?

Regards,

-Kevin

Yes, I think this function would work. Unfortunately, I haven't had any luck figuring out at what level in the code the structures/variables that this routine requires are maintained. I've grepped the code tree for the routines in this source file, but nothing comes up.

Any ideas?

Hi chipslinger,

Which routine are we talking about here XUartLite_Recv() or XUartPs_Recv()?

If you are looking into using XUartPs_Recv(), I see the source code listed in project_14_2project_14_2.sdkSDKSDK_Exportstandalone_bsp_0ps7_cortexa9_0libsrcuartps_v1_01_asrcxuartps.c as I am using a 14.2 standalone example project.

Looks like that function is going to need the XUartPS struct which is in the xuartps.h file:

/**
* The XUartPs driver instance data structure. A pointer to an instance data
* structure is passed around by functions to refer to a specific driver
* instance.
*/
typedef struct {
tXUartPs_Config Config;t/* Configuration data structure */
tu32 InputClockHz;t/* Input clock frequency */
tu32 IsReady;tt/* Device is initialized and ready */
tu32 BaudRate;tt/* Current baud rate */

tXUartPsBuffer SendBuffer;
tXUartPsBuffer ReceiveBuffer;

tXUartPs_Handler Handler;
tvoid *CallBackRef;t/* Callback reference for event handler */
} XUartPs;

Regards,

-Kevin

I have a more basic problem.... Using the default Hello world program, getchar() doesn't work !!!

I checked to make sure the txd/rxd pins are connected in the assignment chart, and I looked on the USB-Serial converter. When I hit a character, it isn't recognized...